The hemodynamic effects of etomidate and midazolam during induction of anaesthesia for coronary artery bypass grafting surgery

The hemodynamic effects of etomidate and midazolam were studied during induction of anesthesia in 30 patients undergoing CABG. The patients were randomly divided into two groups. 0.15 mg/kg midazolam in group M and 0.25 mg/kg etomidate in group E combined with 0.006 mg/kg fentanyl were used for induction of anaesthesia in both groups. Hemodynamic changes were recorded before and after induction, immediately after intubation and 10 minutes after intubation. Heart rate increased significantly after intubation compared to baseline and post induction values in group E (0.05), and only post induction values in group M (p<0.01). Mean arterial pressure and cardiac index decreased significantly after induction in both groups (p<0.01). Pulmonary vascular resistance did not change significantly in both groups. Systemic vascular resistance (SVR) increased significantly 10 minutes after induction in group M (p<0.01). SVR increased significantly after intubation compared to post induction and 10 minutes after intubation according to baseline values (p<0.05) in group E. Arterial elastance increased only after intubation in both groups (p<0.01). Stroke volume decreased significantly after induction in group E (<0.05) and in group M (p<0.01). Etomidate did not alter PAS significantly whereas midazolam decreased PAS significantly in all measurements when compared to control (p<0.05, p<0.01, p<0.01 respectively). Midazolam didn't produce significant changes in pulmonary capillary wedge pressure (PCWP) but etomidate increased PCWP significantly after intubation (p<0.05). Significant differences were found only in PCWP, CI, and SVR when comparing the two groups (p<0.05). We conclude that these two induction agents produce similar effects in the induction period of anesthesia in CABG surgery, but midazolam may be useful in patients with high baseline PCWP.